Manufacturing method of semiconductor device

ABSTRACT

It is an object of the present invention to provide a manufacturing method of a semiconductor device where a semiconductor element is prevented from being damaged and throughput speed thereof is improved, even in a case of thinning or removing a supporting substrate after forming the semiconductor element over the supporting substrate. According to one feature of the present invention, a method for manufacturing a semiconductor device includes the steps of forming a plurality of element groups over an upper surface of a substrate; forming an insulating film so as to cover the plurality of element groups; selectively forming an opening to the insulating film which is located in a region between neighboring two element groups in the plurality of element groups to expose the substrate; forming a first film so as to cover the insulating film and the opening; exposing the element groups by removing the substrate; forming a second film so as to cover the surface of the exposed element groups; and cutting off between the plurality of element groups so as not to expose the insulating film.

TECHNICAL FIELD

The present invention relates to a manufacturing method of asemiconductor device, in particular, to a manufacturing method of asemiconductor device where a supporting substrate is removed afterforming a semiconductor element such as transistor over the supportingsubstrate.

BACKGROUND ART

In recent years, by forming a semiconductor element over a rigidsubstrate such as a glass substrate, a semiconductor device has beenactively developed for use in a display such as an LCD or an organic ELdisplay, a photoelectric conversion element such as a photo sensor or asolar cell, or the like. Besides, a semiconductor device which transmitsand receives data without contact (also referred to as an RFID (RadioFrequency Identification) tag, an ID tag, an IC tag, an IC chip, awireless tag, an electronic tag, or a wireless chip) has been activelydeveloped. In addition, recently, a flexible device such as a film-statedisplay or a semiconductor device embedded in paper has been required,and a reduction in thickness holds an important clue.

In order to reduce thickness of a semiconductor device, there is amethod for using a substrate which is thinned in advance, for example.However, in this case, warpage or the like of the substrate, or, indealing with the element, warpage due to stress, difficulty in handling,misalignment in lithography or a printing step, and the like becomeproblems. Therefore, a method for thinning or removing a substrate afterforming a semiconductor element over the substrate is generally used.

As a method for thinning or removing a substrate, for example, there isa technique for removing a supporting substrate (a glass substrate) bygrinding treatment or polishing treatment, or wet etching using achemical reaction (for example, see Reference 1: Japanese PublishedPatent Application No. 2002-87844).

DISCLOSURE OF INVENTION

However, in a case of removing a substrate, over which a semiconductorelement is formed, by grinding treatment or polishing treatment, thereis a limit of thinning a film due to a limit of accuracy of a device andin-plane uniformity of polishing; therefore, it has been difficult tomake the entire surface have thickness of 50 μm or less; thus, it hasbeen difficult to remove the substrate. In addition, when a substrate issubjected to grinding treatment and polishing treatment, a semiconductorelement provided over the substrate is stressed, thereby having fear ofdamaging the semiconductor element. This is because the semiconductorelement is stressed more significantly as the substrate becomes thinner;therefore, it has been difficult to remove the substrate by grindingtreatment or polishing treatment.

In addition, in a case of removing the substrate, over which thesemiconductor element is formed, by chemical treatment, it is extremelydifficult to remove only the substrate with high yields and uniformly;thus, there has been a problem that it takes up much time to perform thetreatment.

In view of the above problems, it is an object of the present inventionto provide a manufacturing method of a semiconductor device where asemiconductor element is prevented from being damaged and throughputspeed thereof is improved, even in a case of thinning or removing asupporting substrate after forming the semiconductor element over thesupporting substrate.

According to one feature of the present invention, a method formanufacturing a semiconductor device includes the steps of forming aplurality of element groups over an upper surface of a substrate;forming an insulating film so as to cover the plurality of elementgroups; selectively forming an opening to the insulating film which islocated in a region between neighboring two element groups in theplurality of element groups to expose the substrate; forming a firstfilm so as to cover the insulating film and the opening; exposing theelement groups by removing the substrate; forming a second film so as tocover the surface of the exposed element groups; and cutting off betweenthe plurality of element groups so as not to expose the insulating film.

According to another feature of the present invention, a method formanufacturing a semiconductor device includes the steps of forming abase film over an upper surface of a substrate; forming a plurality ofelement groups over the base film; forming an insulating film so as tocover the plurality of element groups; selectively forming an opening tothe insulating film which is located in a region between neighboring twoelement groups in the plurality of element groups to expose thesubstrate or the base film; forming a first film so as to cover theinsulating film and the opening; exposing the base film by removing thesubstrate; forming a second film so as to cover the surface of theexposed base film; and cutting off between the plurality of elementgroups so as not to expose the insulating film.

According to another feature of the present invention, in a method formanufacturing a semiconductor device in the above structures, asubstrate is removed by being thinned from the other side and thenremoving the thinned substrate by chemical treatment using chemicalreaction (chemical reaction treatment (hereinafter, also simply referredto as chemical treatment)). Note that a substrate can be thinned using aphysical means, or a physical means with a chemical means, and forexample, either grinding treatment or polishing treatment, or both canbe used. Chemical treatment can be performed by dipping a thinnedsubstrate into a chemical solution and generating chemical reaction tothe thinned substrate.

Even in a case of removing a substrate over which a semiconductorelement is formed, the semiconductor element is prevented from beingdamaged according to the present invention. Consequently, throughputspeed of a semiconductor device can be improved.

BRIEF DESCRIPTION OF DRAWINGS

In the accompanying drawings:

FIGS. 1A to 1D are views each showing an example of a manufacturingmethod of a semiconductor device of the present invention;

FIGS. 2A to 2D are views each showing an example of a manufacturingmethod of a semiconductor device of the present invention;

FIGS. 3A to 3C are views each showing an example of a manufacturingmethod of a semiconductor device of the present invention;

FIGS. 4A and 4B are views each showing an example of a manufacturingmethod of a semiconductor device of the present invention;

FIGS. 5A to 5D are views each showing an example of a manufacturingmethod of a semiconductor device of the present invention;

FIGS. 6A to 6C are views each showing an example of a manufacturingmethod of a semiconductor device of the present invention;

FIGS. 7A and 7B are views each showing an example of a manufacturingmethod of a semiconductor device of the present invention;

FIGS. 8A and 8B are views each showing an example of a manufacturingmethod of a semiconductor device of the present invention;

FIGS. 9A and 9B are views each showing an example of a manufacturingmethod of a semiconductor device of the present invention;

FIGS. 10A to 10C are a diagram and views each showing an example of anapplication mode of a semiconductor device of the present invention;

FIGS. 11A to 11H are views each showing an example of an applicationmode of a semiconductor device of the present invention;

FIGS. 12A to 12D are views each showing an example of an applicationmode of a semiconductor device of the present invention;

FIGS. 13A and 13B are views each showing an example of an applicationmode of a semiconductor device of the present invention;

FIG. 14 is a view showing an example of an application mode of asemiconductor device of the present invention;

FIGS. 15A to 15F are views each showing an example of an applicationmode of a semiconductor device of the present invention; and

FIG. 16 is a view showing an example of a manufacturing method of asemiconductor device of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment modes of the present invention will be hereinafter explainedwith reference to drawings. However, the present invention is notlimited to the following explanations, and it is to be easily understoodthat various changes and modifications will be apparent to those skilledin the art. Therefore, unless such changes and modifications depart fromthe purport and the scope of the present invention, they should beconstrued as being included therein. Note that, in the structure of thepresent invention that will be hereinafter explained, the same referencenumerals denoting the same portions are used in common in differentdrawings and the explanation is omitted in some cases.

Embodiment Mode 1

This embodiment will explain an example of a manufacturing method of asemiconductor device of the present invention with reference todrawings.

First, an element group 102 is formed over a substrate 101 (FIG. 1A). Inthis embodiment mode, the element group 102 constituting a semiconductordevice is provided in plural over the substrate 101. By forming theelement group 102 in plural over the substrate 101, a plurality ofsemiconductor devices can be manufactured from one substrate, which ispreferable.

As the substrate 101, a glass substrate, a quartz substrate, a metalsubstrate or a stainless steel substrate where an insulating film isformed over one surface, a heat-resistant plastic substrate that canwithstand a processing temperature in this process, or the like ispreferably used. Such a substrate 101 does not have a limit in its areaor shape; therefore, as long as a rectangular substrate one side ofwhich is 1 meter or more is used as the substrate 101, for example,productivity can be improved significantly. Besides, a semiconductorsubstrate such as a Si substrate may also be used.

The element group 102 includes a semiconductor element such as atransistor or a diode, for example. As the transistor, a thin filmtransistor (TFT) where a semiconductor film, which is formed over arigid substrate such as glass, is used as a channel, a field effecttransistor (FET) over a semiconductor substrate such as a Si substrate,where the substrate is used as a channel, an organic TFT where anorganic material is used as a channel, or the like can be provided. Inaddition, as the diode, various diodes such as a variable capacitancediode, a Schottky diode, and a tunnel diode can be applied. In thepresent invention, by using these transistors, diodes, or the like, anysort of integrated circuits including a CPU, a memory, a microprocessor,various sensors such as a temperature sensor; a humidity sensor; and abiosensor, and the like can be provided. Moreover, as the element group102, the present invention includes a mode having an antenna in additionto the semiconductor element such as a transistor. A semiconductordevice where the element group 102 is provided with an antenna can beoperated by using an AC voltage that is generated in the antenna anddata can be transmitted and received without contact with a piece ofexternal equipment (a reader/writer) by modulating an AC voltage that isapplied to the antenna. Note that the antenna may be formed along withan integrated circuit having a transistor or may be electricallyconnected to an integrated circuit after being formed separately fromthe integrated circuit.

Next, an insulating film 103 is formed so as to cover the element group102 (FIG. 1B). The insulating film 103 is provided above a plurality ofthe element groups 102 and between the element groups, and serves as aprotective film of the element group 102.

The insulating film 103 can be provided with a single-layer structure ofan insulating film containing oxygen and/or nitrogen such as a siliconoxide (SiO_(x)) film, a silicon nitride (SiN_(x)) film, a siliconoxynitride (SiO_(x)N_(y)) (X>Y) film, or a silicon nitride oxide(SiN_(x)O_(y)) (X>Y) film, a film containing carbon such as a DLC(diamond like carbon) film, an organic material such as epoxy,polyimide, polyamide, polyvinyl phenol, benzocyclobutene, or acrylic, ora siloxane material such as a siloxane resin; or a stacked structurethereof. Note that the siloxane material corresponds to a materialhaving Si—O—Si bonds. Siloxane has a skeleton formed of a bond ofsilicon (Si) and oxygen (O). As a substituent, an organic groupcontaining at least hydrogen (for example, an alkyl group or aromatichydrocarbon) is used. As a substituent, a fluoro group can also be used.Alternatively, an organic group containing at least hydrogen and afluoro group may be used as a substituent.

Then, an opening 104 is selectively formed in the insulating film 103(FIG. 1C). The opening 104 is selectively formed by irradiating aportion between a plurality of the element groups 102 (here, a portionbetween the neighboring element groups 102) with laser light or by usinga photolithography method. Note that the opening 104 is formed in aportion where the element group 102 is avoided, and here, the opening104 is linearly formed by irradiating a portion between the elementgroups with laser light. Thus, it is preferable that the element group102 be not exposed by forming the opening 104.

Next, a film 105 is formed so as to cover the insulating film 103 andthe opening 104 (FIG. 1D). When a layer including the element group 102,the insulating film 103, and the film 105 (hereinafter, referred to asan element formation layer 110) is separated from the substrate 101, theelement formation layer 110 is prevented from transforming by providingthe film 105. In addition, here, it is preferable to form the film 105so as to fill the opening 104 partially or entirely.

The film 105 can be a film made from polypropylene, polyester, vinyl,polyvinyl fluoride, polyvinyl chloride, or the like, paper of a fibrousmaterial, a laminated film of a base film (polyester, polyamide, aninorganic vapor-deposited film, paper, or the like) and an adhesivesynthetic resin film (an acrylic-based synthetic resin, an epoxy-basedsynthetic resin, or the like), or the like. The film is attached to anobject to be treated by being subjected to heat treatment and pressuretreatment. In performing heat treatment and pressure treatment, anadhesive layer provided over the uppermost surface of the film or alayer (not an adhesive layer) provided over the outermost layer ismelted by heat treatment to be attached by applying pressure. Anadhesive layer may be provided over the surface of the film; however, itis not necessarily provided. The adhesive layer corresponds to a layercontaining an adhesive such as a thermosetting resin, a UV curing resin,an epoxy-based resin, or a resin additive. The film used for sealing ispreferably coated with silica to prevent moisture or the like fromentering the inside after sealing, and for example, a sheet material inwhich an adhesive layer, a film of polyester or the like, and silicacoat are laminated can be used. Thus, the adhesive layers of these filmsare provided so as to fill the opening 104 partially or entirely.

In addition, a hot-melt adhesive can be used as the adhesive layer. Thehot-melt adhesive is formed using a nonvolatile thermoplastic materialthat contains no water or solution, and remains in a solid state at roomtemperature. The hot-melt adhesive is a chemical substance that attachesobjects together by applying the chemical substance in a dissolved stateand cooling it. Further, the hot-melt adhesive has advantages of shortadhesion time and being pollution-free, safe, hygienic, energy-saving,and low-cost. Since the hot-melt adhesive remains in the solid state atnormal temperature, the hot-melt adhesive that has been processed into afilm form or a fiber form in advance can be used. Alternatively, anadhesive layer that is formed over a base film made from polyester orthe like in advance and then is processed into a film form can be used.A film in which a hot-melt film is formed over a base film made frompolyethylene terephthalate is used here. The hot-melt film is formedusing resin with a softening point that is lower than that of the basefilm. By performing heat treatment, only the hot-melt film is dissolvedand becomes a rubbery state so that the dissolved hot-melt film isattached to an object. When cooling the hot-melt film, it is cured. Asthe hot-melt film, for example, a film containing as its main componentethylene-vinyl acetate copolymer (EVA), polyester, polyamide,thermoplastic elastomer, polyolefin, or the like can be used.

Then, the substrate 101 is thinned by a means 107 for thinning a film(FIG. 2A). Here, the substrate 101 is thinned by thinning the substrate101 on which the element group 102 is formed from the opposite side ofthe substrate 101 (back surface) to be a substrate 106. In the case ofthinning the substrate 101, it is preferable to thin as much as possibleto reduce the processing time in the subsequent step (etching bychemical treatment). However, the substrate 101 is likely to be damageddue to the stress applied to the element formation layer 110 as thesubstrate 101 becomes thinner. Therefore, the thickness of the substrate106 is made to be 5 to 50 μm, preferably 5 to 20 μm, and much preferably5 to 10 μm.

As the means 107 for thinning a film, a physical means, and a physicalmeans with a chemical means can be used, and for example, grindingtreatment, polishing treatment, or the like can be used. As for grindingtreatment, an upper surface of an object to be treated (here, a backsurface of the substrate 101) is ground and smoothed using grains of agrinding stone. As for polishing treatment, the upper surface of theobject to be treated is smoothed by a plastic smoothing action orfrictional polishing action using an abrasive agent such asabrasive-coated cloth and paper or abrasive grains. In a case ofperforming grinding treatment or polishing treatment, purified water,polishing solution, or the like can be used. In addition, as polishingtreatment, CMP (Chemical Mechanical Polishing) may also be used.

In this embodiment mode, grinding treatment is performed to the backsurface of the substrate 101 and thereafter polishing treatment isperformed to the back surface of the substrate 101; therefore, thesubstrate 101 is thinned to be the substrate 106. Note that one ofgrinding treatment and polishing treatment may be performed. In the caseof performing either grinding treatment or polishing treatment, or both,it is preferable to thin the substrate 101 as much as possible. However,as the substrate 101 is thinned, the element formation layer 110 islikely to be stressed; thus, there is fear of being damaged due to acrack or the like.

Generally, as shown in FIGS. 4A and 4B, in a case of performing grindingtreatment or polishing treatment to a substrate 101 after forming aninsulating film 103 and a film 105 above an element group 102 withoutproviding an opening 104 (FIG. 4A), a crack 111 is generated in theelement group 102 or the insulating film 103 when an element formationlayer 110 is stressed (FIG. 4B).

On the other hand, in the manufacturing method described in thisembodiment mode, there is a structure where the opening 104 is formedbetween a plurality of the element groups 102 (here, a portion betweenthe neighboring element groups 102) at the phase before subjecting thesubstrate 101 to grinding treatment or polishing treatment. Therefore,there is an advantage that the stress applied to the element group 102and the insulating film 103 is dispersed when the element formationlayer 110 is stressed by grinding treatment or polishing treatment;thus, a crack is unlikely to be generated in the element group 102. Inaddition, when the stress is generated, the damage of the element group102 can be suppressed effectively, as long as the stress is selectivelyapplied to the film 105 provided to the opening 104. Therefore, inconsideration of the material of the insulating film 103 and the film105 covering the element group 102, for example, it is preferable toform the film 105 with a material that is bent more easily than theelement group 102 or the insulating film 103.

The material used for the film 105 preferably has a property of beingbent more easily than that of the element group 102 or the insulatingfilm 103. For example, a material exhibiting elasticity or a materialhaving plasticity can be used. Note that, in the case of using amaterial exhibiting elasticity, the material used for the film 105 isset to have a lower elastic modulus (ratio of stress to strain) thanthat of a material used for the insulating film 103. In the case ofusing a material having plasticity, the material used for the film 105is set to have higher plasticity than that of a material provided in theinsulating film 103. Note that the elasticity here refers to a propertyof an object whose shape or volume is changed by external force toreturn to its original condition after the force is removed. Inaddition, the plasticity here means a property of being easily deformedby external force and kept strained even after removing the force.

In addition, in a case of using a high molecular weight organic compoundor the like having a glass transition temperature as the insulating film103 or the film 105, the material used for the film 105 is set to have alower glass transition point than that of a material used for theinsulating film 103. A material having a low glass transition point hashigher viscoelasticity than that of a material having a high glasstransition point. Therefore, in a case where the material having a lowglass transition and the material having a high glass transition areprovided, large strain is selectively generated in the material having alow glass transition point when stress is applied. Thus, the damage ofthe element group 102 covered with the insulating film 103 can besuppressed.

Next, the thinned substrate 106 is removed by performing chemicaltreatment thereto (FIG. 2B). As chemical treatment, chemical etching isperformed to an object to be treated by using a chemical solution. Here,the etching of the substrate 106 is performed by dipping the substrate106 and the element formation layer 110 into a chemical solution 108.Any chemical solution is accepted as the chemical solution 108 as longas the substrate can be removed, and for example, it is preferable touse a solution containing hydrofluoric acid as the chemical solution 108in a case of using a glass substrate as the substrate 101. Note that, asthe film 105, it is preferable to use a material that is unlikely toreact with the chemical solution 108. In addition, a base film may beformed between the substrate 101 and the element group 102 with amaterial that is unlikely to react with the chemical solution 108. In acase of using a glass substrate as the substrate 101 and removing theglass substrate by being dipped into hydrofluoric acid, it is preferableto provide the base film with nitride, and for example, a single-layerstructure of an insulating film containing nitrogen such as a siliconnitride (SiN_(x)) film, a silicon oxynitride (SiO_(x)N_(y)) (X>Y) film,or a silicon nitride oxide (SiN_(x)O_(y)) (X>Y) film; or a stackedstructure thereof.

Note that, in the above steps, the substrate 101 may be removed bygrinding treatment, polishing treatment, or the like. However, in a caseof performing grinding treatment or polishing treatment with a statewhere the substrate 101 is thinned, it is difficult to obtain a uniformthin film and probability that the damage due to the generation ofstress applied to the element formation layer 110 is increased. On theother hand, the substrate 101 may be removed by using chemical treatmentwithout grinding treatment and polishing treatment; however, in thiscase, there is fear that it takes up much time to remove the substrate101 and throughput speed is decreased. Moreover, there is fear that theelement formation layer 110 has a harmful effect by dipping the elementformation layer in the chemical solution for a long time.

Therefore, in the present invention, after once performing grindingtreatment, polishing treatment, or the like and thinning the substrate101 to some extent when the substrate is removed, the thinned substrateis removed using chemical treatment. Thus, stress or the like applied tothe element formation layer can be suppressed, and throughput speed canbe improved.

Then, a film 109 is formed over one surface of the element formationlayer 110 (a surface where the substrate 101 is removed) to performsealing treatment to the element formation layer 110 (FIG. 2C).

The film 109 can be a film made from polypropylene, polyester, vinyl,polyvinyl fluoride, polyvinyl chloride, or the like, paper of a fibrousmaterial, a laminated film of a base film (polyester, polyamide, aninorganic vapor-deposited film, paper, or the like) and an adhesivesynthetic resin film (an acrylic-based synthetic resin, an epoxy-basedsynthetic resin, or the like), or the like. The film is attached to anobject to be treated by being subjected to heat treatment and pressuretreatment. In performing heat treatment and pressure treatment, anadhesive layer provided over the uppermost surface of the film or alayer (not an adhesive layer) provided over the outermost layer ismelted by heat treatment to be attached by applying pressure. Anadhesive layer may be provided over the surface of the film; however, itis not necessarily provided. The adhesive layer corresponds to a layercontaining an adhesive such as a thermosetting resin, a UV curing resin,an epoxy-based resin, or a resin additive. The film used for sealing ispreferably coated with silica to prevent moisture or the like fromentering the inside after sealing, and for example, a sheet material inwhich an adhesive layer, a film of polyester or the like, and silicacoat are laminated can be used.

In addition, a hot-melt adhesive can be used as the adhesive layer. Thehot-melt adhesive is formed using a nonvolatile thermoplastic materialthat contains no water or solution, and remains in a solid state at roomtemperature. The hot-melt adhesive is a chemical substance that attachesobjects together by applying the chemical substance in a dissolved stateand cooling it. Further, the hot-melt adhesive has advantages of shortadhesion time and being pollution-free, safe, hygienic, energy-saving,and low-cost. Since the hot-melt adhesive remains in the solid state atnormal temperature, the hot-melt adhesive that has been processed into afilm form or a fiber form in advance can be used. Alternatively, anadhesive layer that is formed over a base film made from polyester orthe like in advance and then is processed into a film form can be used.A film in which a hot-melt film is formed over a base film made frompolyethylene terephthalate is used here. The hot-melt film is formedusing resin with a softening point that is lower than that of the basefilm. By performing heat treatment, only the hot-melt film is dissolvedand becomes a rubbery state so that the dissolved hot-melt film isattached to an object. When cooling the hot-melt film, it is cured. Asthe hot-melt film, for example, a film containing as its main componentethylene-vinyl acetate copolymer (EVA), polyester, polyamide,thermoplastic elastomer, polyolefin, or the like can be used.

Next, the element formation layer 110 and the film 109 are cut, and aplurality of the element groups provided over the substrate 101 isseparated into each element group (FIG. 2D). At this time, it ispreferable to separate so that the film 105 and the film 109 are exposedwithout exposing the insulating film 103. This is because, when theinsulating film 103 is exposed, moisture or an impurity element is mixedinto the insulating film 103, thereby deteriorating characteristics ofthe element group 102.

Generally, as shown in FIGS. 3A to 3C, in a case of separating aplurality of the element groups provided over the substrate 101 intoeach element group (FIG. 3C) after forming an insulating film 103 and afilm 105 above an element group 102 without providing an opening 104(FIG. 3A) and removing a substrate 101 to form a film 109 (FIG. 3B),there is a structure where the insulating film 103 is exposed on theside surface. On the other hand, a semiconductor device that is obtainedusing the manufacturing method described in this embodiment mode is madeto have a structure where the opening 104 is formed between a pluralityof the element groups 102 to provide the opening with the film 105 atthe phase before removing the substrate 101. Therefore, as shown in FIG.2D, there can be a structure where the element group 102 and theinsulating film 103 are covered with the film 105 and the film 109 whenseparated into each element. Much specifically, in the structure, theelement group 102 is covered with the insulating film 103 and the film109 without being exposed, and the insulating film 103 is covered withthe film 105 and the film 109 without being exposed. Consequently,moisture or an impurity element is suppressed from entering into theelement group 102 and the insulating film 103, and reliability of asemiconductor device can be improved.

Through the above steps, a semiconductor device can be formed.

Embodiment Mode 2

This embodiment mode will explain a manufacturing method of asemiconductor device which is different from that in the aboveembodiment mode with reference to drawings. Specifically, amanufacturing method of a semiconductor device of the present inventionincluding a thin film transistor, a memory element, and an antenna willbe explained with reference to drawings.

First, an insulating film 202 to be a base is formed over one surface ofa substrate 201, and a semiconductor film 203 is formed over theinsulating film 202 (FIG. 5A). Note that the insulating film 202 and thesemiconductor film 203 can be formed continuously.

As the substrate 201, a glass substrate, a quartz substrate, a metalsubstrate or a stainless steel substrate where an insulating film isformed over one surface, a heat-resistant plastic substrate that canwithstand a processing temperature in this process, or the like ispreferably used. Such a substrate 201 does not have a limit in its areaor shape; therefore, as long as a rectangular substrate one side ofwhich is 1 meter or more is used as the substrate 201, for example,productivity can be improved significantly. Besides, a semiconductorsubstrate such as a Si substrate may also be used.

The insulating film 202 can be provided by a CVD method, a sputteringmethod, or the like with a single-layer structure of an insulating filmcontaining oxygen and/or nitrogen such as a silicon oxide (SiO_(x))film, a silicon nitride (SiN_(x)) film, a silicon oxynitride(SiO_(x)N_(y)) (X>Y) film, or a silicon nitride oxide (SiN_(x)O_(y))(X>Y) film; or a stacked structure thereof. When the insulating film tobe a base has a two-layer structure, for example, it is preferable toform a silicon nitride oxide film as a first layer, and a siliconoxynitride film as a second layer. When the insulating film to be a basehas a three-layer structure, for example, it is preferable to form asilicon oxide film as a first layer, a silicon nitride oxide film as asecond layer, and a silicon oxynitride film as a third layer.Alternatively, it is preferable to form a silicon oxynitride film as afirst layer, a silicon nitride oxide film as a second layer, and asilicon oxynitride film as a third layer. The insulating film to be abase serves as a blocking film that prevents impurities from thesubstrate 201 from entering.

The semiconductor film 203 can be formed with an amorphous semiconductoror a semi-amorphous semiconductor (SAS). Alternatively, apolycrystalline semiconductor film may be used. The SAS has anintermediate structure between an amorphous structure and a crystallinestructure (including a single crystal and a polycrystal) and a thirdstate which is stable in terms of free energy, and the SAS includes acrystalline region having short-range order and lattice distortion. Inat least part of a region of the film, a crystal region of 0.5 to 20 nmcan be observed. In a case of containing silicon as a main component, aRaman spectrum is shifted to a lower wavenumber side than 520 cm⁻¹. Adiffraction peak of (111) or (220) to be caused by a crystal lattice ofsilicon is observed in X-ray diffraction. Hydrogen or halogen of atleast 1 atomic % or more is contained to terminate dangling bonds. TheSAS is formed by performing glow discharge decomposition (plasma CVD) toa gas containing silicon. SiH₄ is given as the gas containing silicon.In addition, Si₂H₆, SiH₂Cl₂, SiHCl₃, SiCl₄, SiF₄, or the like can alsobe used as the gas containing silicon. In addition, GeF₄ may also bemixed. The gas containing silicon may be diluted with H₂, or H₂ and oneor more rare gas elements of He, Ar, Kr, and Ne. A dilution ratiothereof may range from 2 to 1000 times; a pressure, approximately 0.1 to133 Pa; a power supply frequency, 1 to 120 MHz, preferably, 13 to 60MHz; and substrate heating temperatures, 300° C. or less. Aconcentration of an atmospheric constituent impurity such as oxygen,nitrogen, or carbon, as an impurity element in the film, is desirably1×10²⁰ atoms/cm³ or less; in particular, a concentration of oxygen is5×10¹⁹ atoms/cm³ or less, preferably 1×10¹⁹ atoms/cm³ or less. Here, anamorphous semiconductor film is formed in 25 to 200 nm thick(preferably, 30 to 150 nm thick) with a material containing silicon (Si)as its main component (such as Si_(x)Ge_(1−x)) using a sputteringmethod, a CVD method, or the like.

Next, a crystalline semiconductor film is formed by crystallizing theamorphous semiconductor film 203 by a crystallization method such as alaser crystallization method, a thermal crystallization method using RTAor an annealing furnace, a thermal crystallization method using a metalelement which promotes crystallization, or the like. In addition, thecrystallization of the semiconductor film can also be performed bygenerating thermal plasma by application of a DC bias and applying thethermal plasma to the semiconductor film. Then, the obtainedsemiconductor film is etched into a desired shape to form crystallinesemiconductor films 203 a to 203 f, and a gate insulating film 204 isformed so as to cover the semiconductor films 203 a to 203 f (FIG. 5B).

Hereinafter, an example of a manufacturing process of the semiconductorfilms 203 a to 203 f will be briefly explained. First, an amorphoussemiconductor film of 66 nm thick is formed by using a plasma CVDmethod. Next, after holding a solution containing nickel which is ametal element which promotes crystallization over the amorphoussemiconductor film, a crystalline semiconductor film is formed byperforming dehydrogenation treatment (at 500° C. for an hour) andthermal crystallization treatment (at 550° C. for 4 hours) to theamorphous semiconductor film. Thereafter, if necessary, the crystallinesemiconductor film is irradiated with laser light and the crystallinesemiconductor films 203 a to 203 f are formed by using aphotolithography method.

In the case of forming the crystalline semiconductor film with a lasercrystallization method, a continuous wave laser beam (CW laser beam) ora pulsed wave laser beam (pulsed laser beam) can be used. As the laserbeam that can be used here, a laser beam oscillated from one or more ofa gas laser such as an Ar laser, a Kr laser, and an excimer laser; asingle crystal of a YAG laser, a YVO₄ laser, forsterite (Mg₂SiO₄), aYAlO₃ laser, and a GdVO₄ laser or a polycrystal (ceramic) of YAG, Y₂O₃,YVO₄, YAlO₃, and GdVO₄ doped with one or more kinds of Nd, Yb, Cr, Ti,Ho, Er, Tm, and Ta as a dopant; a glass laser; a ruby laser; analexandrite laser; a Ti: sapphire laser; a copper vapor laser; and agold vapor laser can be used. By emitting a laser beam of second tofourth wave of a fundamental wave in addition to a fundamental harmonicof the above laser beams, a crystal having a large grain size can beobtained. For example, a second harmonic (532 nm) or a third harmonic(355 nm) of Nd: YVO₄ laser (fundamental, 1064 nm) can be used. At thistime, the laser requires power density of approximately from 0.01 to 100MW/cm² (preferably, approximately from 0.1 to 10 MW/cm²). The laser isemitted at a scanning rate of approximately 10 to 2000 cm/sec. Note thata laser using, as a medium, single crystal of YAG, YVO₄, forsterite(Mg₂SiO₄), YAlO₃, or GdVO₄ or polycrystal (ceramic) of YAG, Y₂O₃, YVO₄,YAlO₃, or GdVO₄ doped with one or more kinds of Nd, Yb, Cr, Ti, Ho, Er,Tm, and Ta as a dopant; an Ar ion laser; or a Ti: sapphire laser can becontinuously oscillated. Further, pulse oscillation thereof can beperformed with an oscillation frequency of 10 MHz or more by performingQ switch operation, mode synchronization, or the like. When a laser beamis oscillated with a repetition rate of 10 MHz or more, a semiconductorfilm is irradiated with a next pulse during the semiconductor film ismelted by the laser beam and then is solidified. Thus, differing from acase of using a pulse laser with a low repetition rate, a solid-liquidinterface can be continuously moved in the semiconductor film so thatcrystal grains, which continuously grow toward a scanning direction, canbe obtained.

In addition, the crystallization of the amorphous semiconductor film byusing the metal element for promoting crystallization is advantageous inthat the crystallization can be performed at low temperature in shorttime and the direction of crystals becomes uniform, while there is aproblem in that the property is not stable because the off current isincreased due to a residue of the metal element in the crystallinesemiconductor film. Therefore, it is preferable to form an amorphoussemiconductor film serving as a gettering site over the crystallinesemiconductor film. In order to form a gettering site, the amorphoussemiconductor film is required to contain an impurity element such asphosphorous and argon; therefore, the amorphous semiconductor film ispreferably formed by a sputtering method by which argon can be containedat a high concentration. Thereafter, heat treatment (an RTA method,thermal annealing using an annealing furnace, or the like) is performedto diffuse the metal element into the amorphous semiconductor film, andthe amorphous semiconductor film containing the metal element isremoved. Thus, the content of the metal element in the crystallinesemiconductor film can be reduced or removed.

The gate insulating film 204 is formed by a single layer or a stackedlayer of a film containing oxide of silicon or nitride of silicon by aCVD method, a sputtering method, or the like. Specifically, a filmcontaining silicon oxide, a film containing silicon oxynitride, or afilm containing silicon nitride oxide is formed in a single layerstructure or formed by being stacked.

In addition, the gate insulating film 204 may also be formed byperforming high-density plasma treatment to the semiconductor films 203a to 203 f to oxide or nitride surfaces thereof. For example, the gateinsulating film 204 is formed by plasma treatment where a mixed gas of arare gas such as He, Ar, Kr, or Xe; and oxygen, nitrogen oxide (NO₂),ammonia, nitrogen, hydrogen, and the like is introduced. In this case,when excitation of plasma is performed by introducing a microwave,high-density plasma can be generated at a low electron temperature. Thesurfaces of the semiconductor films can be oxidized or nitrided byoxygen radicals (OH radicals may be included) or nitrogen radicals (NHradicals may be included) generated by this high-density plasma.

With such treatment using high-density plasma, the insulating filmhaving a thickness of 1 to 20 nm, typically 5 to 10 nm, is formed overthe semiconductor films. Since a reaction of this case is a solid-phasereaction, an interface state density between the insulating film and thesemiconductor films can be made extremely low. In such high-densityplasma treatment, since the semiconductor films (crystalline silicon orpolycrystalline silicon) are directly oxidized (or nitrided), variationin a thickness of the insulating film that is formed can be ideally madeto be extremely small. In addition, since the semiconductor films in acrystal grain boundary of crystalline silicon are not oxidized too much,an extremely desirable state can be obtained. In other words, in thehigh-density plasma treatment described here, by solid-phase oxidationof the semiconductor film surfaces, the insulating film which hasfavorable uniformity and low interface state density can be formedwithout excessive oxidation in a crystal grain boundary.

As for the gate insulating film, only the insulating film formed byhigh-density plasma treatment may be used. Alternatively, an insulatingfilm of silicon oxide, silicon oxynitride, silicon nitride, or the likemay be deposited or stacked to the insulating film by a CVD method usingplasma or a thermal reaction. In any case, characteristic variation canbe reduced in a transistor including the insulating film formed byhigh-density plasma as part or the entire of the gate insulating film.

Moreover, the semiconductor films 203 a to 203 f, which is obtained byscanning the semiconductor film in one direction to be crystallizedwhile irradiated with a continuous wave laser beam or a laser beamoscillating with a frequency of 10 MHz or more, have a characteristicthat crystals are grown in a scanning direction of the beam. Atransistor (TFT) in which characteristic variation is reduced and fieldeffect mobility is high can be obtained by arranging the transistor sothat the scanning direction is aligned with a channel length direction(a direction in which carriers are flown when a channel forming regionis formed) and by combining the above gate insulating film.

Then, a first conductive film and a second conductive film are stackedover the gate insulating film 204. The first conductive film is formedby a plasma CVD method, a sputtering method, or the like to have athickness of 20 to 100 nm. The second conductive film is formed by aplasma CVD method, a sputtering method, or the like to have a thicknessof 100 to 400 nm. The first conductive film and the second conductivefilm are formed with an element of tantalum (Ta), tungsten (W), titanium(Ti), molybdenum (Mo), aluminum (Al), copper (Cu), chromium (Cr),niobium (Nb), and the like; or an alloy material or a compound materialcontaining the element as its main component. Alternatively, the firstconductive film and the second conductive film are formed with asemiconductor material typified by polycrystalline silicon doped with animpurity element such as phosphorus. As an example of a combination ofthe first conductive film and the second conductive film, a tantalumnitride (TaN) film and a tungsten (W) film, a tungsten nitride (WN) filmand a tungsten film, a molybdenum nitride (MoN) film and a molybdenum(Mo) film, and the like can be given. Since tungsten and tantalumnitride have high heat resistance, heat treatment for thermal activationcan be performed after forming the first conductive film and the secondconductive film. In a case of not a two-layer structure but athree-layer structure, a stacked structure of a molybdenum film, analuminum film, and a molybdenum film is preferably employed.

Next, a resist mask is formed using a photolithography method andetching treatment for forming a gate electrode and a gate line isperformed to form a conductive film (hereinafter, referred to as a gateelectrode 205) serving as a gate electrode. Here, the gate electrode 205is provided with a structure where any of the above materials arestacked.

Then, a resist mask is formed by a photolithography method and animpurity element imparting N-type conductivity is added to thesemiconductor films 203 b, 203 c, 203 e, and 203 f at low concentrationby an ion doping method or an ion implantation method to form N-typeimpurity regions 206. As the impurity element imparting N-typeconductivity, an element belonging to Group 15 is preferably used, andphosphorus (P) or arsenic (As) is used, for example.

Thereafter, a resist mask is formed by a photolithography method and animpurity element imparting P-type conductivity is added to thesemiconductor films 203 a and 203 d to form P-type impurity regions 207.As the impurity element imparting P-type conductivity, boron (B) isused, for example (FIG. 5C).

Next, an insulating film is formed so as to cover the gate insulatingfilm 204 and the gate electrode 205. The insulating film is formed by aplasma CVD method, a sputtering method, or the like with a single-layerstructure or a stacked structure of a film containing an inorganicmaterial such as silicon, oxide of silicon, and/or nitride of silicon,or a film containing an organic material such as an organic resin. Next,the insulating film is selectively etched by anisotropic etching, bywhich etching is performed mainly in a perpendicular direction, to forminsulating films (also referred to as sidewalls) 208 in contact withside faces of the gate electrodes 205. At the same time as themanufacturing of the insulating films 208, the gate insulating film 204is etched to form insulating films 210. The insulating films 208 areused as masks for doping in subsequently forming source and drainregions.

Then, with the use of the resist mask formed by a photolithographymethod and the insulating films 208 as masks, an impurity elementimparting N-type conductivity is added to the semiconductor films 203 b,203 c, 203 e, and 203 f to form first N-type impurity regions 209 a(also referred to as LDD (Lightly Doped Drain) regions) and secondN-type impurity regions 209 b. The concentration of the impurity elementcontained in the first N-type impurity regions 209 a is lower than thatin the second N-type impurity regions 209 b. Through the above steps,N-type thin film transistors 230 b, 230 c, 230 e, and 230 f, and P-typethin film transistors 230 a and 230 d are completed (FIG. 5D).

Note that, in order to form an LDD region, there are a technique ofusing a lower conductive film of a gate electrode, which is formed as astacked structure of two layers or more, as a mask of the gate electrodeby etching or performing anisotropic etching or the like so as toprovided the gate electrode in a tapered shape, and a technique of usingan insulating film which is a sidewall as a mask. A thin film transistorthat is formed by employing the former technique has a structure wherean LDD region is disposed to overlap with a gate electrode byinterposing a gate insulating film therebetween. However, in order toutilize etching or anisotropic etching so as to provide the gateelectrode in a tapered shape in this structure, it is difficult tocontrol the width of the LDD region, and an LDD region cannot be formedin some cases as long as an etching step is not performed preferably. Onthe other hand, with the latter technique of using the insulating filmwhich is a sidewall as a mask, the width of an LDD region can be easilycontrolled, and the LDD region can be formed certainly, as compared withthe former technique.

Subsequently, a single layer or a stacked layer of an insulating film isformed so as to cover the thin film transistors 230 a to 230 f (FIG.6A). The insulating film covering the thin film transistors 230 a to 230f is formed by an SOG method, a droplet discharging method, or the likewith a single layer or a stacked layer of an inorganic material such asoxide of silicon and/or nitride of silicon, an organic material such aspolyimide, polyamide, benzocyclobutene, acrylic, epoxy, or siloxane, orthe like. For example, in a case where the insulating film covering thethin film transistors 230 a to 230 f has a three-layer structure, it ispreferable to form a film containing silicon oxide as an insulating film211 of a first layer, a film containing a resin as an insulating film212 of a second layer, and a film containing silicon nitride as aninsulating film 213 as a third layer.

Note that heat treatment for recovering crystallinity of thesemiconductor films, activating the impurity elements added to thesemiconductor films, or hydrogenating the semiconductor films ispreferably performed before forming the insulating films 211 to 213 orafter forming one or a plurality of the insulating films 211 to 213. Theheat treatment is preferably performed by applying a thermal annealingmethod, a laser annealing method, an RTA method, or the like.

Next, the insulating films 211 to 213 are selectively etched by aphotolithography method to form contact holes which expose thesemiconductor films 203 a to 203 f. Subsequently, a conductive film isformed to fill the contact holes. The conductive film is patterned toform conductive films 214 serving as source and drain wirings.

The conductive films 214 are formed by a CVD method, a sputteringmethod, or the like with a single layer or a stacked layer of an elementof aluminum (Al), tungsten (W), titanium (Ti), tantalum (Ta), molybdenum(Mo), nickel (Ni), platinum (Pt), copper (Cu), gold (Au), silver (Ag),manganese (Mn), neodymium (Nd), carbon (C), and silicon (Si), or analloy material or a compound material containing the element as its maincomponent. The alloy material containing aluminum as its main componentcorresponds to, for example, a material containing aluminum as itscomponent and nickel, or an alloy material containing aluminum as itsmain component, nickel, and either carbon or silicon, or both. Theconductive films 214 may have, for example, a stacked structure of abarrier film, an aluminum silicon (Al—Si) film, and a barrier film, or astacked structure of a barrier film, an aluminum silicon (Al—Si) film, atitanium nitride (TiN) film, and a barrier film. Note that the barrierfilm corresponds to a thin film of titanium, nitride of titanium,molybdenum, or nitride of molybdenum. Aluminum and aluminum silicon havelow resistance and are inexpensive, which are optimum for a material ofthe conductive films 214. When upper and lower barrier layers areprovided, generation of a hillock of aluminum or aluminum silicon can beprevented. By forming the barrier film of titanium that is an elementhaving a high reducing property, even when a thin natural oxide film isformed over the crystalline semiconductor film, the natural oxide filmcan be reduced, so that favorable contact with the crystallinesemiconductor film can be formed.

Then, an insulating film 215 is formed so as to cover the conductivefilms 214 (FIG. 6B). The insulating film 215 is formed with a singlelayer or a stacked layer of an inorganic material or an organic materialby an SOG method, a droplet discharging method, or a printing methodsuch as a screen printing method or a gravure printing method. Inaddition, the insulating film 215 is preferably formed to have athickness of 0.75 to 3 μm.

Subsequently, the insulating film 215 is etched by a photolithographymethod to form contact holes which expose the conductive films 214 inthe thin film transistors 230 a, 230 c, 230 d, and 230 f. Then, aconductive film is formed to fill the contact holes. The conductive filmis formed of a conductive material using a plasma CVD method, asputtering method, or the like. Next, the conductive film is patternedto form conductive films 216 a to 216 d. Note that each of theconductive films 216 b and 216 d serves as one of a pair of conductivefilms included in a memory element that is formed later. Thus, theconductive films 216 b and 216 d are preferably formed with a singlelayer or a stacked layer of titanium, or an alloy material or a compoundmaterial containing titanium as its main component. Titanium has lowresistance, which leads to a reduction in size of a memory element andachievement of higher integration. In a photolithography step to formthe conductive films 216 a to 216 d, wet etching processing ispreferably performed so as not to damage the lower thin film transistors230 a to 230 f, and hydrogen fluoride (HF) or ammonia peroxide ispreferably used as an etchant.

Next, an insulating film 217 is formed so as to cover the end portionsof the conductive films 216 a to 216 d. The insulating film 217 isformed with a single layer or a stacked layer of an inorganic materialor an organic material by an SOG method, a droplet discharging method,or the like. In addition, the insulating film 217 is preferably formedto have a thickness of 0.75 to 3 μm.

Then, a conductive film 218 serving as an antenna is formed in contactwith the conductive films 216 a and 216 c (FIG. 6C). The conductive film218 is formed of a conductive material by a CVD method, a sputteringmethod, a printing method, a droplet discharging method, or the like.Preferably, the conductive film 218 is formed with a single layer or astacked layer of an element of aluminum (Al), titanium (Ti), silver(Ag), copper (Cu), and gold (Au), or an alloy material or a compoundmaterial containing the element as its main component. Specifically, theconductive film 218 is formed by using paste containing silver by ascreen printing method and then performing heat treatment attemperatures of 50 to 350° C. Note that an antenna having a preferablecharacteristic can be obtained by applying pressure at the time of theheat treatment, which is preferable. Alternatively, the conductive film218 is formed by forming an aluminum film by a sputtering method andpatterning the aluminum film. The aluminum film is preferably patternedby wet etching processing, and after the wet etching processing, heattreatment is preferably performed at temperatures of 200 to 300° C.

Next, an organic compound layer 219 serving as a memory element isformed to be in contact with the conductive films 216 b and 216 d (FIG.7A). A material of which property or state changes by an electricaleffect, an optical effect, a thermal effect, or the like is used as amaterial for the memory element. For example, a material, of whichproperty or state changes by melting due to Joule heat, dielectricbreakdown, or the like to cause an upper electrode and a lower electrodeto short, may be used. Therefore, a thickness of a layer used for thememory element (here, the organic compound layer) is preferably 5 to 100nm, much preferably, 10 to 60 nm.

Here, the organic compound layer 219 is formed by a droplet dischargingmethod, a spin coating method, a vapor deposition method, or the like.Subsequently, a conductive film 220 is formed to be in contact with theorganic compound layer 219. The conductive film 220 is formed by asputtering method, a spin coating method, a droplet discharging method,a vapor deposition method, or the like.

Through the above steps, a memory element portion 231 a including astacked body of the conductive film 216 b, the organic compound layer219, and the conductive film 220, and a memory element portion 231 bincluding a stacked body of the conductive film 216 d, the organiccompound layer 219, and the conductive film 220 are completed.

Note that a feature of the above manufacturing steps is to perform thestep of forming the organic compound layer 219 after the step of formingthe conductive film 218 serving as the antenna because heat resistanceof the organic compound layer 219 is not high.

As an organic material used for the organic compound layer, for example,an aromatic amine-based compound (that is, a compound having a benzenering-nitrogen bond) such as4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]-biphenyl (abbreviation: α-NPD),4,4′-bis[N-(3-methylphenyl)-N-phenyl-amino]-biphenyl (abbreviation:TPD), 4,4′,4″-tris(N,N-diphenyl-amino)-triphenylamine (abbreviation:TDATA), 4,4′,4″-tris[N-(3-methylphenyl)-N-phenyl-amino]-triphenylamine(abbreviation: MTDATA), or4,4′-bis(N-(4-(N,N-di-m-tolylamino)phenyl)-N-phenylamino)biphenyl(abbreviation: DNTPD), polyvinyl carbazole (abbreviation: PVK), aphthalocyanine compound such as phthalocyanine (abbreviation: H₂Pc),copper phthalocyanine (abbreviation: CuPc), or vanadyl phthalocyanine(abbreviation: VOPc), or the like can be used. These materials have ahigh hole transporting property.

Besides, a material formed of a metal complex or the like having aquinoline skeleton or a benzoquinoline skeleton such astris(8-quinolinolato)aluminum (abbreviation: Alq₃),tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Almq₃),bis(10-hydroxybenzo[h]-quinolinato)beryllium (abbreviation: BeBq₂), orbis(2-methyl-8-quinolinolato)-4-phenylphenolato-aluminum (abbreviation:BAlq), a material formed of a metal complex or the like having anoxazole-based or thiazole-based ligand such asbis[2-(2′-hydroxyphenyl)benzoxazolato]zinc (abbreviation: Zn(BOX)₂) orbis[2-(2′-hydroxyphenyl)benzothiazolato]zinc (abbreviation: Zn(BTZ)₂),or the like can be used. These materials have a high electrontransporting property.

Other than the metal complexes, a compound or the like such as2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD), 1,3-bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7),3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole(abbreviation: TAZ),3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole(abbreviation: p-EtTAZ), bathophenanthroline (abbreviation: BPhen), orbathocuproin (abbreviation: BCP) can be used.

The organic compound layer may have a single-layer structure or astacked structure. In the case of a stacked structure, materials can beselected from the aforementioned materials to form a stacked structure.Further, the above organic material and a light-emitting material may belaminated. As the light-emitting material,4-dicyanomethylene-2-methyl-6-[2-(1,1,7,7-tetramethyljulolidine-9-yl)ethenyl]-4H-pyran(abbreviation: DCJT),4-dicyanomethylene-2-t-butyl-6-[2-(1,1,7,7-tetramethyljulolidine-9-yl)ethenyl]-4H-pyran,periflanthene,1,4-bis[2-(10-methoxy)-(1,1,7,7-tetramethyljulolidine-9-yl)ethenyl]-2,5-dicyanobenzene,N,N′-dimethylquinacridone (abbreviation: DMQd), coumarin 6, coumarin545T, tris(8-quinolinolato)aluminum (abbreviation: Alq₃),9,9′-bianthryl, 9,10-diphenylanthracene (abbreviation: DPA),9,10-di(2-naphthyl)anthracene (abbreviation: DNA),2,5,8,11-tetra-t-buthylperylene (abbreviation: TBP), or the like can beused.

A layer in which the above light-emitting material is dispersed may beused. In the layer in which the above light-emitting material isdispersed, an anthracene derivative such as9,10-di(2-naphthyl)-2-tert-butylanthracene (abbreviation: t-BuDNA), acarbazole derivative such as 4,4′-di(N-carbazolyl)biphenyl(abbreviation: CBP), a metal complex such asbis[2-(2′-hydroxyphenyl)pyridinato]zinc (abbreviation: Znpp₂) orbis[2-(2′-hydroxyphenyl)benzoxazolato]zinc (abbreviation: ZnBOX), or thelike can be used as a base material. In addition,tris(8-quinolinolato)aluminum (abbreviation: Alq₃),9,10-di(2-naphthyl)anthracene (abbreviation: DNA),bis(2-methyl-8-quinolinolato)-4-phenylphenolato-aluminum (abbreviation:BAlq), or the like can be used.

Such an organic material is changed its property by a thermal effect orthe like; therefore, a glass transition temperature (Tg) thereof ispreferably 50 to 300° C., much preferably, 80 to 120° C.

In addition, a material in which metal oxide is mixed with an organicmaterial or a light-emitting material may be used. Note that thematerial in which metal oxide is mixed includes a state in which metaloxide is mixed or stacked with the above organic material or the abovelight-emitting material. Specifically, it indicates a state which isformed by a co-evaporation method using plural evaporation sources. Sucha material can be referred to as an organic-inorganic compositematerial.

For example, in a case of mixing a substance having a high holetransporting property with metal oxide, it is preferable to use vanadiumoxide, molybdenum oxide, niobium oxide, rhenium oxide, tungsten oxide,ruthenium oxide, titanium oxide, chromium oxide, zirconium oxide,hafnium oxide, or tantalum oxide as the metal oxide.

In a case of mixing a substance having a high electron transportingproperty with metal oxide, it is preferable to use lithium oxide,calcium oxide, sodium oxide, potassium oxide, or magnesium oxide as themetal oxide.

A material of which property changes by an electrical effect, an opticaleffect, or a thermal effect may be used for the organic compound layer;therefore, for example, a conjugated high molecular compound doped witha compound (photoacid generator) which generates acid by absorbing lightcan also be used. As the conjugated high molecular compound,polyacetylenes, polyphenylene vinylenes, polythiophenes, polyanilines,polyphenylene ethynylenes, or the like can be used. As the photoacidgenerator, aryl sulfonium salt, aryl iodonium salt, o-nitrobenzyltosylate, aryl sulfonic acid p-nitrobenzyl ester, sulfonylacetophenones, Fe-arene complex PF6 salt, or the like can be used.

Note that the example of using an organic compound material as thememory element portions 231 a and 231 b is described here; however, thepresent invention is not limited thereto. For example, a phase changematerial such as a material which changes reversibly between acrystalline state and an amorphous state or a material which changesreversibly between a first crystalline state and a second crystallinestate can be used. In addition, a material which changes only from anamorphous state to a crystalline state can also be used.

The material which reversibly changes between a crystalline state and anamorphous state is a material containing a plurality of elements ofgermanium (Ge), tellurium (Te), antimony (Sb), sulfur (S), telluriumoxide (TeOx), tin (Sn), gold (Au), gallium (Ga), selenium (Se), indium(In), thallium (Tl), cobalt (Co), and silver (Ag). For example, amaterial based on Ge—Te—Sb—S, Te—TeO₂—Ge—Sn, Te—Ge—Sn—Au, Ge—Te—Sn,Sn—Se—Te, Sb—Se—Te, Sb—Se, Ga—Se—Te, Ga—Se—Te—Ge, In—Se, In—Se—Tl—Co,Ge—Sb—Te, In—Se—Te, or Ag—In—Sb—Te may be used. The material whichreversibly changes between the first crystalline state and the secondcrystalline state is a material containing a plurality of elements ofsilver (Ag), zinc (Zn), copper (Cu), aluminum (Al), nickel (Ni), indium(In), antimony (Sb), selenium (Se), and tellurium (Te), for example,Ag—Zn, Cu—Al—Ni, In—Sb, In—Sb—Se, or In—Sb—Te. When using this material,a phase change is carried out between two different crystalline states.The material which changes only from an amorphous state to a crystallinestate is a material containing a plurality of elements of tellurium(Te), tellurium oxide (TeO_(x)), palladium (Pd), antimony (Sb), selenium(Se), and bismuth (Bi), for example, Te—TeO₂, Te—TeO₂—Pd, orSb₂Se₃/Bi₂Te₃.

Next, an insulating film 221 serving as a protective film is formed byan SOG method, a spin coating method, a droplet discharging method, aprinting method, or the like to cover the memory element portions 231 aand 231 b and the conductive film 218 serving as the antenna. Theinsulating film 221 is formed of a film containing carbon such as DLC(Diamond Like Carbon), a film containing silicon nitride, a filmcontaining silicon nitride oxide, or an organic material, preferably, anepoxy resin.

Then, as described in the above embodiment mode, an opening isselectively formed in an element formation layer 233 having the thinfilm transistors 230 a to 230 f, the conductive film 218 serving as theantenna, the memory element portions 231 a and 231 b, and the like, anda film 222 is formed so as to fill the element formation layer 233 andthe opening (FIG. 7B).

The film 222 can be a film made from polypropylene, polyester, vinyl,polyvinyl fluoride, polyvinyl chloride, or the like, paper of a fibrousmaterial, a laminated film of a base film (polyester, polyamide, aninorganic vapor-deposited film, paper, or the like) and an adhesivesynthetic resin film (an acrylic-based synthetic resin, an epoxy-basedsynthetic resin, or the like), or the like. The film is attached to anobject to be treated by being subjected to heat treatment and pressuretreatment. In performing heat treatment and pressure treatment, anadhesive layer provided over the uppermost surface of the film or alayer (not an adhesive layer) provided over the outermost layer ismelted by heat treatment to be attached by applying pressure. Anadhesive layer may be provided over the surface of the film; however, itis not necessarily provided. The adhesive layer corresponds to a layercontaining an adhesive such as a thermosetting resin, a UV curing resin,an epoxy-based resin, or a resin additive. The film used for sealing ispreferably coated with silica to prevent moisture or the like fromentering the inside after sealing, and for example, a sheet material inwhich an adhesive layer, a film of polyester or the like, and silicacoat are laminated can be used.

Next, the substrate 201 is thinned to be a substrate 224 by performingeither grinding treatment or polishing treatment, or both to thesubstrate 201 (FIG. 8A). Here, the side of the substrate 201 on whichthe element formation layer 223 is not formed (back surface) issubjected to grinding treatment, and thereafter, the back surface of thesubstrate 201 is further subjected to polishing treatment to thin thesubstrate 201, thereby obtaining the substrate 224. It is preferable tothin the substrate 201 as much as possible in the case of performinggrinding treatment or polishing treatment to the substrate 201. However,the element formation layer 233 is easily stressed as the substrate 201gets thinner; therefore, the substrate 224 is made to have a thicknessof 5 to 50 μm, preferably 5 to 20 μm, and much preferably 5 to 10 μm.

Then, the substrate 224 is removed by chemical treatment (FIG. 8B). Aschemical treatment, chemical etching is performed to an object to betreated by using a chemical solution. Here, the etching of the substrate224 is performed by dipping the substrate 224 and the element formationlayer 233 into a chemical solution. Any chemical solution is accepted asthe chemical solution as long as the substrate can be removed, and forexample, it is preferable to use a solution containing hydrofluoric acidas the chemical solution in a case of using a glass substrate as thesubstrate 201. Note that, as the film 222, it is preferable to use amaterial that is unlikely to react with the chemical solution, and aninsulating film containing an epoxy resin is used here. In addition,since the insulating film 202 is in direct contact with the chemicalsolution after removing the substrate 201, it is preferable to use amaterial that has resistance to the chemical solution as the insulatingfilm 202. For example, the insulating film 202 is provided preferably ina two-layer structure, where a silicon nitride oxide film is formed as afirst layer and a silicon oxynitride film is formed as a second layer.

Next, sealing treatment is performed by providing a film 225 for a sideof the element formation layer 233 (FIG. 9A). As the sealing treatment,the film 225 is provided on one side of the element formation layer 233(a side on which the substrate 201 is removed), and the film 225 is madeto attach to the element formation layer 233 by using a roller 243 asshown in FIG. 16.

The film 225 for sealing can be a film made from polypropylene,polyester, vinyl, polyvinyl fluoride, polyvinyl chloride, or the like,paper of a fibrous material, a laminated film of a base film (polyester,polyamide, an inorganic vapor-deposited film, paper, or the like) and anadhesive synthetic resin film (an acrylic-based synthetic resin, anepoxy-based synthetic resin, or the like), or the like. The film isattached to an object to be treated by being subjected to heat treatmentand pressure treatment. In performing heat treatment and pressuretreatment, an adhesive layer provided over the uppermost surface of thefilm or a layer (not an adhesive layer) provided over the outermostlayer is melted by heat treatment to be attached by applying pressure.An adhesive layer may be provided over the surface of the film 225;however, it is not necessarily provided. The adhesive layer correspondsto a layer containing an adhesive such as a thermosetting resin, a UVcuring resin, an epoxy-based resin, or a resin additive. The film usedfor sealing is preferably coated with silica to prevent moisture or thelike from entering the inside after sealing, and for example, a sheetmaterial in which an adhesive layer, a film of polyester or the like,and silica coat are laminated can be used.

For example, as the film 225, a film where a hot-melt adhesivecontaining a thermoplastic resin is provided over a base film such aspolyethylene terephthalate can be used. The hot-melt adhesive remains ina solid state at room temperature but is dissolved by applying heat.Therefore, a surface of the element formation layer 233 is provided withthe film having the hot-melt adhesive and then subjected to heattreatment and pressure treatment by the roller 243; thus, the elementformation layer 233 can be sealed. Note that, in the case of performingheat treatment with the roller 243, the treatment has to be performed atsuch a high temperature that the hot-melt adhesive is dissolved enough.Accordingly, in a case of using metal such as aluminum for a stage 241,there is fear that heat generated by the roller 243 is drawn to thestage 241; thus, the hot-melt adhesive is not dissolved enough.Therefore, it is preferable to provide a thermal insulation materialsuch as silicon rubber between the stage 241 and an object to betreated.

As the film 222 and the film 225, a film subjected to antistatictreatment for preventing static electricity or the like (hereinafter,referred to as an antistatic film) may also be used. An antistatic filmincludes a film where an antistatic material is dispersed in a resin, afilm to which an antistatic material is attached, and the like. A filmcontaining an antistatic material may be a film having one side providedwith an antistatic material, or a film having the both sides providedwith an antistatic material. Further, in a film having one side providedwith an antistatic material, a side containing an antistatic materialmay be attached to the inside or outside of the film. Note that anantistatic material may be provided over the entire surface or part of afilm. An antistatic material herein includes metal, oxide of indium andtin (ITO), and a surfactant such as a zwitterionic surfactant, acationic surfactant, and a nonionic surfactant. Instead, a resinmaterial containing a cross-linked copolymer high molecular compoundhaving a carboxyl group and a quaternary ammonium base in a side chainmay be used as an antistatic material. An antistatic film may beobtained by attaching, kneading, or applying these materials to a film.When a semiconductor device is sealed with an antistatic film, thesemiconductor element can be protected from external static electricityor the like when being handled as a product.

Note that, after performing sealing treatment of the element formationlayer 233 with the film 225, sealing may be performed so as to cover thefilm 222, if necessary.

Then, the element formation layer 233, the film 222, and the film 225are cut to separate into each element (FIG. 9B). At this time, it ispreferable to separate so that the film 222 and the film 225 are exposedwithout exposing the element formation layer 233. By covering theelement formation layer 233 with the film 222 and the film 225completely in such a manner, an impurity element or moisture issuppressed from mixing into a semiconductor element such as a thin filmtransistor from outside; thus, a highly reliable semiconductor devicecan be obtained.

Note that this embodiment mode can be implemented by being arbitrarilycombined with the above embodiment mode. In other words, the material orthe formation method described in the above embodiment mode can be usedin combination also in this embodiment mode, and the material or theformation method described in this embodiment mode can be used incombination also in the above embodiment mode.

Embodiment Mode 3

This embodiment mode will explain an example of application modes of asemiconductor device that is obtained by using the manufacturing methoddescribed in the above embodiment mode. Specifically, applications of asemiconductor device which can exchange data without contact will beexplained below with reference to drawings. The semiconductor devicewhich can exchange data without contact is also referred to as an RFID(Radio Frequency Identification) tag, an ID tag, an IC tag, an IC chip,an RF (Radio Frequency) tag, a wireless tag, an electronic tag, or awireless chip, depending on application modes.

A semiconductor device 80 has the function of communicating data withoutcontact, and includes a high frequency circuit 81, a power supplycircuit 82, a reset circuit 83, a clock generation circuit 84, a datademodulation circuit 85, a data modulation circuit 86, a control circuit87 for controlling other circuits, a memory circuit 88, and an antenna89 (FIG. 10A). The high frequency circuit 81 is a circuit which receivesa signal from the antenna 89 and outputs a signal received by the datamodulation circuit 86 from the antenna 89. The power supply circuit 82is a circuit which generates power supply potential from the receivedsignal. The reset circuit 83 is a circuit which generates a resetsignal. The clock generation circuit 84 is a circuit which generatesvarious clock signals based on the received signal inputted from theantenna 89. The data demodulation circuit 85 is a circuit whichdemodulates the received signal and outputs the signal to the controlcircuit 87. The data modulation circuit 86 is a circuit which modulatesa signal received from the control circuit 87. As the control circuit87, a code extraction circuit 91, a code determination circuit 92, a CRCdetermination circuit 93, and an output unit circuit 94 are provided,for example. Note that the code extraction circuit 91 is a circuit whichseparately extracts a plurality of codes included in an instructiontransmitted to the control circuit 87. The code determination circuit 92is a circuit which compares the extracted code and a code correspondingto a reference to determine the content of the instruction. The CRCcircuit is a circuit which detects the presence or absence of atransmission error or the like based on the determined code.

In addition, the number of memory circuits to be provided is not limitedto one, and may be plural. An SRAM, a flash memory, a ROM, a FeRAM, orthe like, or a circuit using the organic compound layer described in theabove embodiment mode in a memory element portion can be used.

Then, an example of operation of a semiconductor device which cancommunicate data without contact of the present invention will beexplained. First, a radio signal is received by the antenna 89. Theradio signal is transmitted to the power supply circuit 82 via the highfrequency circuit 81, and high power supply potential (hereinafterreferred to as VDD) is generated. The VDD is supplied to each circuitincluded in the semiconductor device 80. In addition, a signaltransmitted to the data demodulation circuit 85 via the high frequencycircuit 81 is demodulated (hereinafter, a demodulated signal). Further,a signal transmitted through the reset circuit 83 and the clockgeneration circuit 84 via the high frequency circuit 81 and thedemodulated signal are transmitted to the control circuit 87. The signaltransmitted to the control circuit 87 is analyzed by the code extractioncircuit 91, the code determination circuit 92, the CRC assessmentcircuit 93, and the like. Then, in accordance with the analyzed signal,information of the semiconductor device stored in the memory circuit 88is outputted. The outputted information of the semiconductor device isencoded through the output unit circuit 94. Furthermore, the encodedinformation of the semiconductor device 80 is transmitted by the antenna89 as a radio signal through the data modulation circuit 86. Note thatlow power supply potential (hereinafter, VSS) is common among aplurality of circuits included in the semiconductor device 80, and VSScan be set to GND.

Thus, data of the semiconductor device can be read by transmitting asignal from a reader/writer to the semiconductor device 80 and receivingthe signal transmitted from the semiconductor device 80 by thereader/writer.

In addition, the semiconductor device 80 may supply a power supplyvoltage to each circuit by an electromagnetic wave without a powersource (battery) mounted, or by an electromagnetic wave and a powersource (battery) with the power source (battery) mounted.

Since a semiconductor device which can be bent can be manufactured byusing the structure shown in the above embodiment mode, thesemiconductor device can be provided over an object having a curvedsurface by attachment.

Next, an example of application modes of a semiconductor device whichcan exchange data without contact will be explained. A side face of aportable terminal including a display portion 3210 is provided with areader/writer 3200, and a side face of an article 3220 is provided witha semiconductor device 3230 (FIG. 10B). When the reader/writer 3200 isheld over the semiconductor device 3230 included in the article 3220,information on the article 3220 such as a raw material, the place oforigin, an inspection result in each production process, the history ofdistribution, or an explanation of the article is displayed on thedisplay portion 3210. In addition, when a product 3260 is transported bya conveyor belt, the product 3260 can be inspected using a reader/writer3240 and a semiconductor device 3250 provided over the product 3260(FIG. 10C). Thus, by utilizing the semiconductor device for a system,information can be acquired easily, and improvement in functionality andadded value of the system can be achieved. As shown in the aboveembodiment mode, a transistor or the like included in a semiconductordevice can be prevented from being damaged even when the semiconductordevice is attached to an object having a curved surface, and a reliablesemiconductor device can be provided.

In addition, as a signal transmission method in the above semiconductordevice which can exchange data without contact, an electromagneticcoupling method, an electromagnetic induction method, a microwavemethod, or the like can be used. The transmission system may beappropriately selected by a practitioner in consideration of an intendeduse, and an optimum antenna may be provided in accordance with thetransmission method.

In a case of employing, for example, an electromagnetic coupling methodor an electromagnetic induction method (for example, a 13.56 MHz band)as the signal transmission method in the semiconductor device,electromagnetic induction is caused by a change in magnetic fielddensity. Therefore, the conductive film serving as the antenna is formedin an annular shape (for example, a loop antenna) or a spiral shape (forexample, a spiral antenna).

In a case of employing, for example, a microwave method (for example, aUHF band (860 to 960 MHz band), a 2.45 GHz band, or the like) as thesignal transmission method in the semiconductor device, the shape suchas a length of the conductive film serving as an antenna may beappropriately set in consideration of a wavelength of an electromagneticwave used for signal transmission. For example, the conductive filmserving as an antenna can be formed in a linear shape (for example, adipole antenna (FIG. 12A)), a flat shape (for example, a patch antenna(FIG. 12B)), a ribbon shape (FIGS. 12C and 12D), or the like. The shapeof the conductive film serving as an antenna is not limited to a linearshape, and the conductive film serving as an antenna may be provided ina curved-line shape, a meander shape, or a combination thereof, inconsideration of a wavelength of an electromagnetic wave.

The conductive film serving as an antenna is formed with a conductivematerial by a CVD method, a sputtering method, a printing method such asscreen printing or gravure printing, a droplet discharging method, adispenser method, a plating method, or the like. The conductive materialis formed with a single-layer structure of an element of aluminum (Al),titanium (Ti), silver (Ag), copper (Cu), gold (Au), platinum (Pt),nickel (Ni), palladium (Pd), tantalum (Ta), and molybdenum (Mo), or analloy material or a compound material containing these elements as itsmain component; or a stacked structure thereof.

In a case of forming a conductive film serving as an antenna by, forexample, a screen printing method, the conductive film can be providedby selectively printing conductive paste in which conductive particleseach having a grain size of several nm to several tens of μm aredissolved or dispersed in an organic resin. As the conductive particles,one or more of metal particles such as silver (Ag), gold (Au), copper(Cu), nickel (Ni), platinum (Pt), palladium (Pd), tantalum (Ta),molybdenum (Mo), and titanium (Ti), fine particles of silver halide, ordispersible nanoparticles can be used. In addition, as the organic resinincluded in the conductive paste, one or a plurality of organic resinseach serving as a binder, a solvent, a dispersant, or a coating of themetal particle can be used. Typically, an organic resin such as an epoxyresin or a silicon resin can be used. In forming a conductive film,baking is preferably performed after the conductive paste is applied.For example, in a case of using fine particles (the grain size of whichis 1 to 100 nm) containing silver as its main component as a material ofthe conductive paste, a conductive film can be obtained by curing theconductive paste by baking at temperatures of 150 to 300° C.Alternatively, fine particles containing solder or lead-free solder asits main component may be used; in this case, it is preferable to use afine particle having a grain size of 20 μm or less. Solder or lead-freesolder has an advantage such as low cost.

Besides the above material, ceramic, ferrite, or the like may be appliedto an antenna. Further, a material of which dielectric constant andmagnetic permeability are negative in a microwave band (metamaterial)can be applied to an antenna.

In a case of applying an electromagnetic coupling method or anelectromagnetic induction method, and providing a semiconductor deviceincluding an antenna in contact with metal, a magnetic material havingmagnetic permeability is preferably provided between the semiconductordevice and metal. In the case of providing a semiconductor deviceincluding an antenna in contact with metal, an eddy current flows inmetal accompanying change in magnetic field, and a demagnetizing fieldgenerated by the eddy current impairs a change in magnetic field anddecreases a communication distance. Therefore, an eddy current of metaland a decrease in communication range can be suppressed by providing amaterial having magnetic permeability between the semiconductor deviceand metal. Note that ferrite or a metal thin film having high magneticpermeability and little loss of high frequency wave can be used as themagnetic material.

In a case of providing an antenna, a semiconductor element such as atransistor and a conductive film serving as an antenna may be directlyformed over one substrate, or a semiconductor element and a conductivefilm serving as an antenna may be provided over separate substrates andthen attached to be electrically connected to each other.

Note that an applicable range of the flexible semiconductor device iswide in addition to the above, and the flexible semiconductor device canbe applied to any product as long as it clarifies information such asthe history of an object without contact and is useful for production,management, or the like. For example, the semiconductor device can bemounted on paper money, coins, securities, certificates, bearer bonds,packing containers, books, recording media, personal belongings,vehicles, food, clothing, health products, commodities, medicine,electronic devices, and the like. Examples thereof will be explainedwith reference to FIGS. 11A to 11H.

The paper money and coins are money distributed to the market andinclude one valid in a certain area (cash voucher), memorial coins, andthe like. The securities refer to checks, certificates, promissorynotes, and the like (FIG. 11A). The certificates refer to driver'slicenses, certificates of residence, and the like (FIG. 11B). The bearerbonds refer to stamps, rice coupons, various gift certificates, and thelike (FIG. 11C). The packing containers refer to wrapping paper for foodcontainers and the like, plastic bottles, and the like (FIG. 11D). Thebooks refer to hardbacks, paperbacks, and the like (FIG. 11E). Therecording media refers to DVD software, video tapes, and the like (FIG.11F). The vehicles refer to wheeled vehicles such as bicycles, ships,and the like (FIG. 11G). The personal belongings refer to bags, glasses,and the like (FIG. 11H). The food refers to food articles, drink, andthe like. The clothing refers to clothes, footwear, and the like. Thehealth products refer to medical instruments, health instruments, andthe like. The commodities refer to furniture, lighting equipment, andthe like. The medicine refers to medical products, pesticides, and thelike. The electronic devices refer to a liquid crystal display device,an EL display device, a television device (a TV set and a flat-screen TVset), a cellular phone, and the like.

Forgery can be prevented by providing the paper money, the coins, thesecurities, the certificates, the bearer bonds, or the like with thesemiconductor device. The efficiency of an inspection system, a systemused in a rental shop, or the like can be improved by providing thepacking containers, the books, the recording media, the personalbelongings, the food, the commodities, the electronic devices, or thelike with the semiconductor device. Forgery or theft can be prevented byproviding the vehicles, the health products, the medicine, or the likewith the semiconductor device; further, in a case of the medicine,medicine can be prevented from being taken mistakenly. The semiconductordevice can be mounted on the foregoing article by being attached to thesurface or being embedded therein. For example, in a case of a book, thesemiconductor device may be embedded in a piece of paper; in a case of apackage made from an organic resin, the semiconductor device may beembedded in the organic resin. By using a flexible semiconductor device,breakage or the like of an element included in the semiconductor devicecan be prevented even when the semiconductor device is mounted on paperor the like.

As described above, the efficiency of an inspection system, a systemused in a rental shop, or the like can be improved by providing thepacking containers, the recording media, the personal belonging, thefood, the clothing, the commodities, the electronic devices, or the likewith the semiconductor device. In addition, by providing the vehicleswith the semiconductor device, forgery or theft can be prevented.Moreover, by implanting the semiconductor device in a creature such asan animal, an individual creature can be easily identified. For example,by implanting the semiconductor device with a sensor in a creature suchas livestock, its health condition such as a current body temperature aswell as its birth year, sex, breed, or the like can be easily managed.

Note that this embodiment mode can be implemented by being arbitrarilycombined with the above embodiment mode. In other words, the material orthe formation method described in the above embodiment mode can be usedin combination also in this embodiment mode, and the material or theformation method described in this embodiment mode can be used incombination also in the above embodiment mode.

Embodiment Mode 4

This embodiment mode will explain an example of application modes of asemiconductor device that is obtained by using the manufacturing methoddescribed in the above embodiment mode. Specifically, a semiconductordevice having a displaying means will be explained with reference todrawings.

First, as a displaying means, a case of providing a pixel portion with alight-emitting element will be explained with reference to FIGS. 13A and13B. Note that FIG. 13A shows a top view showing an example of asemiconductor device of the present invention, whereas FIG. 13B shows across-sectional view of FIG. 13A taken along lines a-b and c-d.

As shown in FIG. 13A, a semiconductor device shown in this embodimentmode includes a scanning line driver circuit 502, a signal line drivercircuit 503, a pixel portion 504, and the like which are provided over afilm 225 (a film-like substrate). In addition, a film 222 (a film-likesubstrate) is provided so as to sandwich the pixel portion 504 with thefilm 225. The scanning line driver circuit 502, the signal line drivercircuit 503, and the pixel portion 504 can be provided by forming thinfilm transistors each having any of the structures shown in the aboveembodiment mode over the film 225.

The scanning line driver circuit 502 and the signal line driver circuit503 receive a video signal, a clock signal, a start signal, a resetsignal, or the like from an FPC (Flexible Printed Circuit) 507 servingas an external input terminal. Note that only the FPC is shown here;however, the FPC may be provided with a printed wiring board. Inaddition, as a thin film transistor, which forms the signal line drivercircuit 503 or the scanning line driver circuit 502, a structure wherethin film transistors are stacked can be employed as shown in the aboveembodiment mode. By providing thin film transistors by being stacked, anarea in which the signal line driver circuit 503 or the scanning linedriver circuit 502 is occupied can be reduced; therefore, the pixelportion 504 can be formed to have a large area.

FIG. 13B is a schematic view of a cross section in FIG. 13A taken alonglines a-b and c-d. Here, a case where thin film transistors included inthe signal line driver circuit 503 and the pixel portion 504 areprovided over the film 225 is shown. A CMOS circuit that is acombination of an n-type thin film transistor 510 a and a p-type thinfilm transistor 510 b having any of the structure shown in the aboveembodiment mode is formed as the signal line driver circuit 503.

A thin film transistor that forms a driver circuit such as the scanningline driver circuit 502 or the signal line driver circuit 503 may beformed using a CMOS circuit, a PMOS circuit, or an NMOS circuit. Adriver integration type in which a driver circuit such as the scanningline driver circuit 502 or the signal line driver circuit 503 is formedover the film 225 is described in this embodiment mode; however, it isnot necessarily required, and a driver circuit can be formed outside thefilm 225 instead of over the film 225.

The pixel portion 504 is formed with a plurality of pixels eachincluding a light-emitting element 516 and a thin film transistor 511for driving the light-emitting element 516. A thin film transistorhaving any of the structures shown in the above embodiment mode can beapplied to the thin film transistor 511. Here, a first electrode 513 isprovided so as to be connected to a conductive film 214 connected to asource or drain region of the thin film transistor 511, and aninsulating film 217 is formed to cover an end portion of the firstelectrode 513. The insulating film 217 serves as a partition in aplurality of pixels.

As the insulating film 217, a positive type photosensitive acrylic resinfilm is used here. The insulating film 217 is formed to have a curvedsurface at an upper end portion or a lower end portion thereof in orderto make the coverage favorable. For example, in a case of using positivetype photosensitive acrylic as a material of the insulating film 217,the insulating film 217 is preferably formed to have a curved surfacewith a curvature radius (0.2 to 3 μm) only at an upper end portion.Either a negative type which becomes insoluble in an etchant by lightirradiation or a positive type which becomes soluble in an etchant bylight irradiation can be used as the insulating film 217. Alternatively,the insulating film 217 can be provided with a single-layer structure ofan organic material such as epoxy, polyimide, polyamide,polyvinylphenol, or benzocyclobutene, or a siloxane resin; or a stackedstructure thereof. As shown in the above embodiment mode, the surface ofthe insulating film 217 can be modified to obtain a dense film bysubjecting the insulating film 217 to plasma treatment and oxidizing ornitriding the insulating film 217. By modifying the surface of theinsulating film 217, intensity of the insulating film 217 can beimproved, and physical damage such as crack generation at the time offorming an opening or the like or film reduction at the time of etchingcan be reduced. In addition, by modifying the surface of the insulatingfilm 217, interfacial quality such as adhesion with a light-emittinglayer 514 to be provided over the insulating film 217 is improved.

In addition, in the semiconductor device shown in FIGS. 13A and 13B, thelight-emitting layer 514 is formed over the first electrode 513, and asecond electrode 515 is formed over the light-emitting layer 514. Thelight-emitting element 516 is provided with a stacked structure of thefirst electrode 513, the light-emitting layer 514, and the secondelectrode 515.

One of the first electrode 513 and the second electrode 515 is used asan anode, and the other is used as a cathode.

A material having a high work function is preferably used for an anode.For example, a single-layer film such as an ITO film, an indium tinoxide film containing silicon, a transparent conductive film formed by asputtering method using a target in which indium oxide is mixed withzinc oxide (ZnO) of 2 to 20 wt %, a zinc oxide (ZnO) film, a titaniumnitride film, a chromium film, a tungsten film, a Zn film, or a Pt film;a stacked layer of a titanium nitride film and a film containingaluminum as its main component; a three-layer structure of a titaniumnitride film, a film containing aluminum as its main component, andanother titanium nitride film; or the like can be used. When a stackedstructure is employed, the electrode can have low resistance as a wiringand form a favorable ohmic contact. Further, the electrode can serve asan anode.

A material having a low work function (Al, Ag, Li, Ca, or an alloythereof such as MgAg, MgIn, AlLi, CaF₂, or Ca₃N₂) is preferably used fora cathode. In a case where an electrode used as a cathode is made totransmit light, a stacked layer of a metal thin film with a smallthickness and a transparent conductive film (ITO, indium tin oxidecontaining silicon, a transparent conductive film formed by a sputteringmethod using a target in which indium oxide is mixed with zinc oxide(ZnO) of 2 to 20 wt %, zinc oxide (ZnO), or the like) is preferably usedas the electrode.

Here, the first electrode 513 is formed using ITO which has alight-transmitting property as an anode, and light is extracted from thefilm 225 side. Note that light may be extracted form the film 222 sideby using a material having a light-transmitting property for the secondelectrode 515, or light can be extracted from both the film 225 side andthe film 222 side by forming the first electrode 513 and the secondelectrode 515 with a material having a light-transmitting property (thisstructure is referred to as dual emission).

The light-emitting layer 514 can be formed with a single layer or astacked structure of a low molecular material, an intermediate molecularmaterial (including an oligomer and a dendrimer), or a high molecularmaterial (also referred to as a polymer) by a method such as a vapordeposition method using an evaporation mask, an ink-jet method, or aspin coating method.

Note that the semiconductor device including a pixel portion is notlimited to the above structure using a light-emitting element in a pixelportion as described above, and it also includes a semiconductor deviceusing liquid crystals in a pixel portion. The semiconductor device usingliquid crystals in a pixel portion is shown in FIG. 14.

FIG. 14 shows one example of a semiconductor device having liquidcrystals in a pixel portion. Liquid crystals 522 are provided between anorientation film 521 provided to cover a conductive film 214 and a firstelectrode 513 and an orientation film 523 provided over a film 222. Inaddition, a second electrode 524 is provided to be in contact with thefilm 222. An image is displayed by controlling light transmittance bycontrolling a voltage applied to the liquid crystals provided betweenthe first electrode 513 and the second electrode 524. Moreover, a spacer525 is provided in the liquid crystals 522 to control the distance (cellgap) between the first electrode 513 and the second electrode 524.

As described above, in the semiconductor device described in thisembodiment mode, the pixel portion can be provided with a light-emittingelement or liquid crystals.

Next, application modes of a semiconductor device having the above pixelportion will be explained with reference to drawings.

The following electronic devices can be given as application modes of asemiconductor device having the above pixel portion: a camera such as avideo camera or a digital camera, a goggle type display (head mounteddisplay), a navigation system, an audio reproducing device (car audio,an audio component, and the like), a computer, a game machine, aportable information terminal (a mobile computer, a cellular phone, aportable game machine, an electronic book, and the like), an imagereproducing device provided with a recording medium (specifically, adevice capable of processing data in a recording medium such as adigital versatile disc (DVD) and having a display which can display theimage of the data), and the like. Hereinafter, specific examples thereofwill be described.

FIG. 15A shows a display, which includes a main body 4101, a supportingstand 4102, a display portion 4103, and the like. The display portion4103 is formed using a flexible substrate, which can realize alightweight and thin display. In addition, the display portion 4103 canbe curved, and can be detached from the support 4102 and the display canbe mounted along a curved wall. Thus, the flexible display can beprovided over a curved portion as well as a flat surface; therefore, itcan be used for various applications. A flexible display, which is oneapplication mode of a semiconductor device of the present invention, canbe manufactured by using the flexible semiconductor device described inthis embodiment mode or the above embodiment mode for the displayportion 4103, a circuit, or the like.

FIG. 15B shows a display that can be wound, which includes a main body4201, a display portion 4202, and the like. Since the main body 4201 andthe display portion 4202 are formed using a flexible substrate, thedisplay can be carried in a bent or wound state. Therefore, even in acase where the display is large-size, the display can be carried in abag in a bent or wound state. A flexible, lightweight, and thinlarge-sized display, which is one application mode of a semiconductordevice of the present invention, can be manufactured by using theflexible semiconductor device shown in this embodiment mode or the aboveembodiment mode for the display portion 4202, a circuit, or the like.

FIG. 15C shows a sheet-type computer, which includes a main body 4401, adisplay portion 4402, a keyboard 4403, a touch pad 4404, an externalconnection port 4405, a power plug 4406, and the like. The displayportion 4402 is formed using a flexible substrate, which can realize alightweight and thin computer. In addition, the display portion 4402 canbe wound and stored in the main body by providing a portion of the mainbody 4401 with a storage space. Moreover, also by forming the keyboard4403 to be flexible, the keyboard 4403 can be wound and stored in thestorage space of the main body 4401 in a similar manner to the displayportion 4402, which is convenient for carrying around. The computer canbe stored without taking a place by bending when it is not used. Aflexible, lightweight, and thin computer, which is one application modeof a semiconductor device of the present invention, can be manufacturedby using the flexible semiconductor device shown in this embodiment modeor the above embodiment mode for the display portion 4402, a circuit, orthe like.

FIG. 15D shows a display device having a 20 to 80-inch large-sizeddisplay portion, which includes a main body 4300, a keyboard 4301 thatis an operation portion, a display portion 4302, a speaker 4303, and thelike. The display portion 4302 is formed using a flexible substrate, andthe main body 4300 can be carried in a bent or wound state with thekeyboard 4301 detached. In addition, the connection between the keyboard4301 and the display portion 4302 can be performed without wires. Forexample, the main body 4300 can be mounted along a curved wall and canbe operated with the key board 4301 without wires. In this case, aflexible, lightweight, and thin large-sized display device, which is oneapplication mode of a semiconductor device of the present invention, canbe manufactured by using the flexible semiconductor device shown in thisembodiment mode or the above embodiment mode for the display portion4302, a circuit, or the like.

FIG. 15E shows an electronic book, which includes a main body 4501, adisplay portion 4502, operation keys 4503, and the like. In addition, amodem may be incorporated in the main body 4501. The display portion4502 is formed using a flexible substrate and can be bent or wound.Therefore, the electronic book can also be carried without taking aplace. Further, the display portion 4502 can display a moving image aswell as a still image such as a character. A flexible, lightweight, andthin electronic book, which is one application mode of a semiconductordevice of the present invention, can be manufactured by using theflexible semiconductor device shown in this embodiment mode or the aboveembodiment mode for the display portion 4502, a circuit, or the like.

FIG. 15F shows an IC card, which includes a main body 4601, a displayportion 4602, a connection terminal 4603, and the like. Since thedisplay portion 4602 is formed to be a lightweight and thin sheet typeusing a flexible substrate, it can be formed over a card surface byattachment. When the IC card can receive data without contact,information obtained from the outside can be displayed on the displayportion 4602. A flexible, lightweight, and thin IC card, which is oneapplication mode of a semiconductor device of the present invention, canbe manufactured by using the flexible semiconductor device shown in thisembodiment mode or the above embodiment mode for the display portion4602, a circuit, or the like.

As described above, an applicable range of a semiconductor device of thepresent invention is so wide that the semiconductor device of thepresent invention can be applied to electronic devices of variousfields. Note that this embodiment mode can be implemented by beingarbitrarily combined with the above embodiment mode. In other words, thematerial or the formation method described in the above embodiment modecan be used in combination also in this embodiment mode, and thematerial or the formation method described in this embodiment mode canbe used in combination also in the above embodiment mode.

This application is based on Japanese Patent Application serial no.2005-288141 filed in Japan Patent Office on Sep. 30 in 2005, the entirecontents of which are hereby incorporated by reference.

EXPLANATION OF REFERENCE

-   101. substrate, 102. element group, 103. insulating film, 104.    opening, 105. film, 106. substrate, 107. means for thinning a film,    108. chemical solution, 109. film, 110. element formation layer,    111. crack, 201. substrate, 202. insulating film, 203. semiconductor    film, 203 a, semiconductor film, 203 b, semiconductor film, 203 c,    semiconductor film, 203 d, semiconductor film, 203 e, semiconductor    film, 203 f semiconductor film, 204. gate insulating film, 205. gate    electrode, 206. N-type impurity region, 207. P-type impurity region,    208. insulating film, 209 a, first N-type impurity region, 209 b,    second N-type impurity region, 210. insulating film, 211. insulating    film, 212. insulating film, 213. insulating film 214. conductive    film, 215. insulating film, 216 a, conductive film, 216 b,    conductive film, 216 c, conductive film, 216 d, conductive film,    217. insulating film, 218. conductive film, 219. organic compound    layer, 220. conductive film, 221. insulating film, 222. film, 224.    substrate, 225. film, 230 a, thin film transistor, 230 b, thin film    transistor, 230 c, thin film transistor, 230 d, thin film    transistor, 230 e, thin film transistor, 230 f, thin film    transistor, 231 a, memory element portion, 231 b, memory element    portion, 233. element formation layer, 241. stage, 243. roller, 80.    semiconductor device, 81. high frequency circuit, 82. power supply    circuit, 83. reset circuit, 84. clock generation circuit, 85. data    demodulation circuit, 86. data modulation circuit, 87. control    circuit, 88. memory circuit, 89. antenna, 91. code extraction    circuit, 92. code determination circuit, 93. CRC determination    circuit, 94. output unit circuit, 3210. display portion, 3200.    reader/writer, 3220. article, 3230. semiconductor device, 3240.    reader/writer, 3250. semiconductor device, 3260. article, 502.    scanning line driver circuit, 503. signal line driver circuit, 504.    pixel portion, 510 a, thin film transistor, 510 b, thin film    transistor, 511. thin film transistor, 513. first electrode, 514.    light-emitting layer, 515. second electrode, 516. light-emitting    element, 521. orientation film, 522. liquid crystal, 523.    orientation film, 524. second electrode, 525. spacer, 4101. main    body, 4102. supporting stand, 4103. display portion, 4201. main    body, 4202. display portion, 4401. main body, 4402. display portion,    4403. keyboard, 4404. touch pad, 4405. external connection port,    4406. power plug, 4300. main body, 4301. keyboard, 4302. display    portion, 4303. speaker, 4501, main body, 4502, display portion,    4503. operation keys, 4601. main body, 4602. display portion, and    4603. connection terminal.

1. A semiconductor device comprising: a first insulating film; anelement group over the first insulating film, the element groupcontaining a thin film transistor interposed between a plurality ofinsulating films and an antenna electrically connected to the thin filmtransistor; a protective film covering the thin film transistor and theantenna; and a second insulating film covering a top surface and a sidesurface of the protective film, wherein each of the first insulatingfilm and the second insulating film contains at least one ofpolypropylene, polyester, vinyl, polyvinyl fluoride, polyvinyl chloride,and paper of a fibrous material.
 2. A semiconductor device according toclaim 1, wherein the semiconductor device is one of an RFID tag, an IDtag, an IC tag, an IC chip, an RF tag, a wireless tag, an electronictag, and a wireless chip.
 3. A semiconductor device according to claim1, wherein the protective film contains a diamond-like-carbon.
 4. Asemiconductor device comprising: a first insulating film; an elementgroup over the first insulating film, the element group containing athin film transistor interposed between a plurality of insulating filmsand an antenna electrically connected to the thin film transistor; aprotective film covering the thin film transistor and the antenna; and asecond insulating film over the protective film, wherein a portion ofthe second insulating film is in contact with the first insulating film,wherein each of the first insulating film and the second insulating filmcontains at least one of polypropylene, polyester, vinyl, polyvinylfluoride, polyvinyl chloride, and paper of a fibrous material.
 5. Asemiconductor device according to claim 4, wherein the semiconductordevice is one of an RFID tag, an ID tag, an IC tag, an IC chip, an RFtag, a wireless tag, an electronic tag, and a wireless chip.
 6. Asemiconductor device according to claim 4, wherein the protective filmcontains a diamond-like-carbon.
 7. A semiconductor device comprising: afirst insulating film; an element group over the first insulating film,the element group containing a thin film transistor interposed between aplurality of insulating films and an antenna electrically connected tothe thin film transistor; a protective film covering the thin filmtransistor and the antenna; and a second insulating film covering a topsurface and a side surface of the protective film, wherein a sidesurface of the first insulating film is aligned with a side surface ofthe second insulating film, wherein each of the first insulating filmand the second insulating film contains at least one of polypropylene,polyester, vinyl, polyvinyl fluoride, polyvinyl chloride, and paper of afibrous material.
 8. A semiconductor device according to claim 7,wherein the semiconductor device is one of an RFID tag, an ID tag, an ICtag, an IC chip, an RF tag, a wireless tag, an electronic tag, and awireless chip.
 9. A semiconductor device according to claim 7, whereinthe protective film contains a diamond-like-carbon.
 10. A semiconductordevice comprising: a first insulating film; an element group over thefirst insulating film, the element group containing a thin filmtransistor interposed between a plurality of insulating films and anantenna electrically connected to the thin film transistor; a protectivefilm covering the thin film transistor and the antenna; and a secondinsulating film over the protective film, wherein a portion of thesecond insulating film is in contact with the first insulating film, andwherein a side surface of the first insulating film is aligned with aside surface of the second insulating film, wherein each of the firstinsulating film and the second insulating film contains at least one ofpolypropylene, polyester, vinyl, polyvinyl fluoride, polyvinyl chloride,and paper of a fibrous material.
 11. A semiconductor device according toclaim 10, wherein the semiconductor device is one of an RFID tag, an IDtag, an IC tag, an IC chip, an RF tag, a wireless tag, an electronictag, and a wireless chip.
 12. A semiconductor device according to claim10, wherein the protective film contains a diamond-like-carbon.